A Resonant Dual Half Bridge And Full Bridge Three-port DC-DC Converter

With the development and utilization of renewable energy and the rapid development of power electronics technology,DC microgrid systems have received widespread attention.The traditional two-port DC converters used in DC microgrids can no longer meet the urgent needs of high power density and high efficiency conversion.Aiming at this problem,a fully isolated resonant dual half-bridge and full-bridge three-port DC-DC converter is proposed in this paper,and the principle and characteristics of the converter are studied.First,the basic working principle of the resonant dual half-bridge and full-bridge three-port DC-DC converter is explained in detail in this article.The fundamental wave analysis method is used for modeling analysis,and the star and angular models of the three-port converter are derived.Then,the average power of the three ports is calculated by the vector analysis method;the influence of the resonant tank parameters on the characteristics of tche resonant current peak value and the output voltage is analyzed.Through time domain analysis,the ZVS soft switching constraint conditions of each port are obtained,and the relationship between the soft switching of the three ports and the circuit parameters is analyzed.Secondly,based on the mathematical model that has been obtained,the small signal model of the converter is obtained by Taylor expansion of the average output voltage of port 3 and the average current of port 2 at a certain operating point,which highlights the coupling between the two control degrees of freedom.In view of this problem,the principle of hardware decoupling is studied,and the decoupling method is applied to the proposed converter including the LC resonant tank.The hardware decoupling was simulated and verified in PSIM.Then,in view of the problem that the converter contains a lot of magnetic components,a magnetic integration scheme is proposed.By selecting the appropriate shape of the magnetic core and using the KCL and KVL of the magnetic circuit to mathematically model the integrated magnetic core,the influence of the magnetic column air gap size on the degree of coupling between the integrated inductors is analyzed according to the model,and a set of air gap values that meet the requirements is obtained by iterative calculation in Mathematica.Therefore,low coupling integrated inductors is realized.The Magnetic integration scheme was simulated and verified in Ansoft Maxwell.And the transformer ratio parameters and transformer core are designed and selected according to the conclusion of matching gain.Finally,based on the simulation analysis,an experimental prototype with a rated power of 740 W was built based on the TMS320F28335 DSP.The experimental results verified the correctness of the converter’s working principle and the proposed decoupling and magnetic integration scheme.